Which method is commonly used to extract copper from low-grade ores?

The correct option is Phytomining. This answer is correct because it matches the approved learning objective to distinguish extracting copper from low-grade ores from extracting metals by reduction with carbon in the subtopic Alternative methods of extracting metals.

The correct option is Phytomining. Phytomining is correct because it directly supports the approved learning objective to distinguish extracting copper from low-grade ores from extracting metals by reduction with carbon. This belongs to the subtopic Alternative methods of extracting metals within Using the Earth's resources and obtaining potable water, so the explanation must stay tied to that curriculum context. The other options are incorrect because they either do not answer this learning objective, use a vague statement, or move away from Alternative methods of extracting metals.